Analysis of hole wall defects of drilled carbon fiber reinforced polymer laminates

The hole wall defects created during drilling of carbon fiber reinforced polymer laminates are analyzed. First, an analysis of the location of the defects on the wall is performed. It is shown that, using results of orthogonal cutting, it is possible to predict the location of the main defects. Then refined scanning electron microscopic observation shows the different patterns of the defects. These observations raise the question of the quantification and measurement of the quality of holes drilled in composite laminates. Two roughness parameters, Ra and the bearing surface are compared and significant differences are found. This study is a contribution to a better definition of quality indicators for machined surfaces in composite structures, which should help to limit overquality and production costs.